pset_assign.2 (2010 09)

p
pset_assign(2) pset_assign(2)
NAME
pset_assign() - change processor set assignment
SYNOPSIS
#include <sys/pset.h>
int pset_assign(
psetid_t pset ,
spu_t spu,
psetid_t *opset
);
DESCRIPTION
The pset_assign()
function assigns the processor spu to the processor set pset , removing the proces-
sor spu from its current processor set. A processor may not belong to more than one processor set at any
given time. If opset is not
NULL
, it contains the processor set ID of the previously assigned processor set
upon successful operation.
A user with the
PSET privilege or a user with WRITE permissions on the processor sets may change the
processor set assignment for a processor using the
pset_assign() function. A user without the
PSET
privilege must have WRITE permissions in both processor sets to make the processor reassignment,
unless the target processor set is the system default processor set. That is, only a user with the
PSET
privilege may move a processor out of the system default processor set.
Currently, processor 0 cannot be reassigned to another processor set from the system default processor
set. The system default processor set is never empty.
If pset is
PS_DEFAULT or PS_NONE, the processor spu is assigned to the system default processor set.
If pset is
PS_QUERY, the processor’s assignment is not changed, but the current processor set ID of pro-
cessor spu is returned in opset . Neither WRITE permission nor the PSET privilege is needed for
PS_QUERY operation.
If there are threads or processes with binding to the processor spu (in its old processor set), the binding of
affected threads and processes is changed to another processor in that processor set. If spu is the last
processor in the locality domain that contributes to its current processor set and there are threads or
processes with binding to the locality domain, their binding is changed to another locality domain in the
processor set. See mpctl(2) for binding to processors and locality domains.
If spu is the last processor in its current processor set, the behavior of
pset_assign()
is dependent on
the value of the
PSET_ATTR_LASTSPU
attribute. The following attribute values are defined for this
attribute:
PSET_ATTRVAL_DFLTPSET
Assign the processor to the specified processor set, and migrate all threads and processes to the
system default processor set,
PS_DEFAULT. This is the default behavior. If the threads and
processes being migrated to the system default processor set (pset ) have binding to processor
or locality domain, their binding is reassigned to another processor or locality domain in the
system default processor set.
PSET_ATTRVAL_FAIL
Make the request fail if there are active threads and processes assigned to the processor set.
Security Restrictions
Some or all of the actions associated with this system call require the
PSET privilege. Processes owned
by the superuser have this privilege. Processes owned by other users may have this privilege, depending
on system configuration. See privileges (5) for more information about privileged access on systems that
support fine-grained privileges.
Note on Logical Processor and Hyper-Threading Feature
On systems with the Hyper-Threading (HT) feature enabled at the firmware, each hyper-thread is
represented as a logical processor (LCPU).
For pset_assign(), migration of a logical processor in a processor core may also migrate that logical
processor’s sibling logical processor, which belongs to the same physical processor core. Otherwise the
resulting configuration would violate the processor set contract, which specifies that applications bound to
a processor set have complete and exclusive control of all processor cores within that processor set.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1